Indexing mechanism for automatic gun



Oct. 21, 1958 H. A. ROBINSON' 2,856,822

INDEXING MECHANISM FOR AUTOMATIC GUN Filed Aug. 21, 1956 s Sheets-Sheet 1 Oct. 21, 1958 H. A. RCBINSON 2,856,822

INDEXING MECHANISM FOR AUTOMATIC GUN Filed Aug. 21, 1956 3 Sheets-Sheet 5 IN VEN TOR.

United States Patent Ofiice 2,856,822 Patented Oct. 21, 1958 KNDEXING MECHANISM FQR AUTOMATIC GUN Hugh A. Robinson, Belmont, Mass., assignor to the United States of America as represented by the Secretary of the Army Application August 21, 1956, Serial No. 605,454

4 Claims. (Cl. 89-156) My invention relates to an automatic gun having a cartridge drum with retractable positioning rollers and more particularly to such a gun in which the rollers are link-connected for simultaneous fixed cam operation.

Conventional revolver-type guns are provided with cam operated, spring-biased rollers to position the drum.

It is an object of my invention to provide a positive operating device for controlling the drum position.

Another object of my invention is to provide such a gun with link-connected, axially-slidable rollers and a rigid cam for engagement therewith to control the drum.

Other aims and objects of my invention will appear from the following explanation thereof.

In carrying out my invention, a four chamber drum is provided with index rollers disposed on intermediately mounted shafts having the inner ends thereof link-connected in series for alternate retraction of the pairs of opposite rollers with the drum. An actuator reciprocally operable responsive to discharge of cartridges in the chambers is provided with a closed cam track for engagement with the rollers to sequentially retain the chambers in the firing station of the gun during discharge of the cartridges therein and to control rotation of the drum. The cam is provided with an inclined floor for engagement with the ends of the rollers for retraction thereof into the drum.

For a more complete understanding, reference is directed to the following description and the accompanying drawing thereof in which:

, Fig. 1 is a reduced elevational view in partial crosssection of a gun incorporating one embodiment of my invention;

Fig. 2 is a view along line 22 of Fig. 1 with the actuator in battery position;

Fig. 3 is a view similar to Fig. 2 with the actuator in a rearward position;

Fig. 4 is an enlarged view along line 4-4 of Fig. 2;

Fig. 5 is a fragmentary view of the drum slots;

Fig. 6 is a perspective view of a carriage and a roller;

Fig 7 is a plan view of the actuator; and

Fig. ii is a perspective view of the actuator.

Accordingly, an automatic gun 12 includes a recoil unit 14 with a barrel 16 and a drum 18 having four chambers 19 for inclosing cartridges 20 and a removable rearward portion 21.

Drum 18 is provided with carriages 22 radially slidable in slots 23 intermediately disposed between chambers 19, and rollers 24 are rotatably disposed on stub shafts 25 of carriages 22. The carriages are provided with inwardly projecting ends 26. Drum 18 includes inclosure 28 and links 30 are disposed therein and serially secured to ends 26 by fasteners 32 to form a collapsible parallelogram whereby movement of one of the pairs of diametrically opposed rollers 24 between operating positions, projecting from drum 18, and retracted positions therein moves the other pair of the rollers to the alternate ones of such positions. Carriages 22 include opposing flanges 36 to engage slots 38 for torsional stability of the carriages.

Drum 18 is disposed for sequential rotation of chambers 19 to stations including a pair of ramming stations for insertion of cartridges 26 into the chambers, a firing station in axial alignment with barrel 16 for discharge of cartridges 20 therein and an extraction station for removal of the cases of the fired cartridges from drum 18.

An actuator 42 in recoil unit 14 is provided with a cam track 44 for engagement with a roller in the operating position. The actuator is biased to a battery position and a dwell portion 46 of cam track 44 engages one of the rollers to retain the chamber corresponding thereto in the firing station for the discharge. Actuator 42 is .disposed for slidable axial reciprocation in rearward and forward strokes responsive to the discharge and a curved portion 48 of cam track 44 cooperates with the rollers 24 received therein to rotate the following chamber to the firing station responsive to the reciprocation. A straight portion 50 of cam track 44 includes a ramp 52 for engagement with shaft 25 of the operating position roller to reverse the positions of the pairs of rollers and dispose the following roller in dwell portion 46.

Wings 54 are provided on recoil unit 14 respectively adjacent the sides of actuator 42 for engagement with the ends of rollers 24 to retain the corresponding pair of rollers in the retracted positions, as shown in Fig. 3.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In an automatic gun including a recoil unit provided with a barrel, and a rotatable drum having diametricallyopposed chambers for cartridges arranged in normally related pairs and a firing station for the chambers in axial alignment with the barrel for discharge of the cartridges therethrough, an indexing device comprising rollers symmetrically disposed intermediate the chambers and connected for alternate radial actuation in opposed pairs between respective positions of retraction within the drum and of operation protruding therefrom, and an actuator for axial reciprocation in the recoil unit responsive to the discharge provided with a closed cam track engageable with said rollers in the operation positions for rotation of the drum and reversal of the positions of said pairs responsive to the reciprocation to successively convey the chambers to the firing station.

2. An indexing device as described in claim 1 provided with wings disposed on the recoil unit for retaining said rollers in the retraction positions.

3. An indexing device as described in claim 1 with carriages slidably disposed in the drum and provided with shafts for respectively supporting said rollers, and said indexing device also including links in serial relation connecting the inner ends of said carriages for the alternate radial actuation of opposite pairs of said rollers between respective positions of retraction Within the drum and of operation protruding therefrom.

4. An indexing device as described in claim 3 with said shafts provided with projecting ends and said cam track provided with a ramp for engagement with said ends for the reversal of the positions of said pairs.

References Cited in the file of this patent FOREIGN PATENTS 697,934 Great Britain Sept. 30, 1953 

